Headfoil-type shavers typically have dual 9-12-mm-D cylindrical bladed or perforated cutters reciprocated ±1-mm axially against headfoils at 8K-cpm as part of 3-6-g cutting mechanisms with effective cutting areas of under 3-cm2, while a few faster models have inversely less. Rotary shavers have 2-3 narrow flat circular cutting areas, partially compensated by higher cutter scan velocity.
Shaver mechanism designs have changed little and performance has improved minimally since headfoils of current thinness were developed decades ago. Basic designs are over a half-century old, and many old designs still being sold shave as well as new ones.